1. Field of the Invention
This invention relates to a method for enabling organic chlorine compounds produced in various chemical reactions such as the polymerization of high molecular compounds to be incinerated so that the waste gas released from the incinerator will contain a very small amount of chlorine gas.
2. Description of the Prior Art
An organic chlorine compound, on combustion, produces a combustion gas which contains hydrochloric acid gas and chlorine gas. Although the chlorine gas content of such a combustion gas is variable with the particular kind of organic chlorine compound and the conditions of combustion involved, it is generally on the order of at least hundreds of ppm. In an extreme case, it may reach 30,000 ppm.
Since the chlorine gas is a deadly poison, the chlorine gas concentration in an exhaust gas released into the ambient air is controlled most rigidly. Any person incinerating an organic chlorine compound, therefore, is required to decrease the chlorine gas concentration in the exhaust gas from the incinerator to the fullest possible extent.
A particularly effective method for this purpose has been disclosed by Japanese Patent Laid-open Publication No. SHO 49-17371. This method relates to combustion of an organic chlorine compound in the form of a solution.
Generally, combustion of an organic chlorine compound in the form of a solution results in formation of carbon monoxide, carbon dioxide, hydrogen chloride, nitrogen, oxygen, chlorine and steam. In this case, the occurrence of chlorine gas and hydrochloric acid gas is involved in an equilibrated reaction represented by the following formula: EQU 4HCl+O.sub.2 .revreaction.2Cl.sub.2 +2H.sub.2 O
The equilibrium constant (K.sub.1) of this reaction, therefore, is expressed as follows: ##EQU1##
Where T stands for the temperature, therefore, K.sub.1 and T have a fixed relation such that K.sub.1 decreases with the increasing value of T.
The foregoing explanation clearly indicates that the following measures should be taken to lower the amount of chlorine gas formed in the reaction indicated above.
(1) A measure to lower the temperature of combustion.
(2) A measure to increase the partial pressure of water.
(3) A measure to decrease the partial pressure of oxygen.
The invention disclosed by the patent laid-open publication cited above relates to a method which comprises mixing the solution of a given organic chlorine compound with water or an aqueous solution, subjecting the mixture to combustion and, at the same time, directly spraying water or the aqueous solution onto the flame of combustion. The specification of the cited publication implies that an ordinary combustion furnace is used in working the invention so disclosed. According to what is described in the specification, a minor part of the amount of water required for the method is first used for mixing with the organic chlorine compound and the remaining major amount of water is sprayed onto the flame of combustion. By the method disclosed in the specification, however, it is difficult for the gas (namely, the flame of combustion) under treatment to be sufficiently mixed with water. Thus, the degree to which the chlorine concentration in the exhaust gas under treatment can be decreased by this method is limited.
Also there is a high possibility that the organic chlorine compound under treatment may contain a substance such as an alkali which, upon combustion, produces a low-melting compound. Since such a low-melting compound escapes being removed by the ordinary method of combustion such as is disclosed by the aforementioned patent laid-open publication, it brings about a disadvantage that the spray nozzle is clogged to the extent of lowering the efficiency of combustion and the compound adheres, either in its unaltered form or in the form of a salt, to the interior walls of the furnace and duct.